He probably won't get too suspicious if you get 100% on three quizzes when you regularly get A's in that class. A ninety-something percent jump to a 100 is less than a 10-point increase.
That being said, it's still best to learn the math so that you don't become dependent on using Brainly for every question. Maybe only use it when you're having a lot of trouble with a particular problem or concept; but some of the explanations on here are actually really helpful in teaching things.
